1. Field of the Invention
The present invention relates to a liquid crystal display (LCD) device and more particularly, to a liquid crystal display (LCD) device having a black seal pattern, an external resin pattern, and method of fabricating the same.
2. Discussion of the Related Art
Among the many types of flat panel display devices being currently developed, liquid crystal display (LCD) devices have been most commonly used for notebook and desktop computers because of their superior high resolution, color displaying ability, and quality of displayed images. In general, LCD devices make use of optical anisotropy and polarization properties of liquid crystal layer to display image data. The LCD devices have upper and lower substrates each having electrodes thereon and a liquid crystal layer interposed therebetween. The LCD devices display images by forming an electric field between the upper and lower substrates to align liquid crystal molecules, thereby controlling light transmissivity according to alignment of the liquid crystal molecules.
FIG. 1 is a plan view of a liquid crystal display (LCD) panel according to the related art. In FIG. 1, a liquid crystal display (LCD) device includes an array substrate 50 and a color filter substrate 60, wherein the array substrate 50 commonly has a larger area than the color filter substrate 60. A black matrix 65 is formed along edges of the color filter substrate 60, and a seal pattern 70 is formed on the black matrix 65. Although not shown in FIG. 1, liquid crystal material is injected into a space that is bounded by the seal pattern 70 between the array and color filter substrates 50 and 60. The liquid crystal display (LCD) device has active and non-active areas A1 and NA1 that are divided by the black matrix 65. For example, an area of the liquid crystal display (LCD) device that is surrounded by the black matrix 65 is the active area A1, and an outer area of the black matrix 65 is the non-active area NA1. The active area A1 is a region where images are actually displayed and includes a plurality of pixels. For simplicity, a black matrix has been omitted but is formed in a boundary of each pixel. A plurality of gate and data lines 52 and 53 are formed in the active area A1, and pixel regions (not shown) are defined by crossings of the gate and data lines 52 and 53. In addition, a thin film transistor (not shown) is formed at a position adjacent to the crossing of the gate and data lines 52 and 53. Gate and data pads 54 and 55 to which the gate and data lines are respectively connected are formed in marginal spaces of the array substrate 50, and are electrically connected to gate and data driving circuits (not shown), respectively.
FIG. 2 is a cross-sectional view of the liquid crystal display (LCD) panel of FIG. 1 according to the related art. In FIG. 2, the active area A1 functions to display images and the non-active area NA1 includes regions occupied by the gate and data pads 54 and 55 and the black matrix 65 (in FIG. 1). A black matrix 21 covers gate and data links (not shown) that are usually formed at a boundary region between the active area A1 and the non-active area NA1. A gate electrode 11 is formed in the active area A1 on a transparent first substrate 10, commonly referred to as an array substrate, with conductive metal material. In addition, a gate insulating layer 12 is formed on the transparent first substrate 10 and includes inorganic insulating materials, such as silicon oxide (SiO2) and silicon nitride (SiNx). An active layer 13 and an ohmic contact layer 14 are sequentially formed on the gate insulating layer 12 in a position corresponding to the gate electrode 11. The active layer 13 is formed of amorphous silicon (a-Si:H) and the ohmic contact layer 14 is formed of impurity-doped amorphous silicon (n+a-Si:H or p+a-Si:H). Source and drain electrodes 15a and 15b spaced apart from each other are formed on the ohmic contact layer 14 using conductive metal materials. The gate electrode 11, the active layer 13, the ohmic contact layer 14, the source electrode 15a, and the drain electrode 15b form a thin film transistor “T,” wherein the gate electrode 11 is electrically connected to the gate line 52 (in FIG. 1) and the source electrode 15a is electrically connected to the data line 53 (in FIG. 1).
A passivation layer 16 is formed on the thin film transistor “T” and an entire surface of the transparent first substrate 10 using one of silicon nitride (SiNx) and silicon oxide (SiO2). Then, a drain contact hole 16c is formed through the passivation layer 16 to expose a portion of the drain electrode 15b. A pixel electrode 17 is formed on the passivation layer 16 in a region corresponding to the pixel region, and is electrically connected to the drain electrode 15b via the drain contact hole 16c. A transparent second substrate 20, commonly referred to as a color filter substrate, is spaced apart from the transparent first substrate 10. A black matrix 21a is formed on an inner surface of the transparent second substrate 20 in a region corresponding to the thin film transistor “T” of the transparent first substrate 10. In addition, the black matrix 21 is further formed in the non-active area NA1 to cover the gate and data links.
A color filter 22 is formed beneath the black matrix 21a in the active area A1 to display red (R), green (G), and blue (B) colors, and a common electrode 23 formed of transparent conductive metal materials is formed on the color filter 22. A liquid crystal layer 30 is formed between the transparent first and second substrates 10 and 20 by injecting liquid crystal material into a space between the first and second substrates 10 and 20 and bounded by a seal pattern 40. The gate insulating layer 12 and the passivation layer 16 on the first substrate 10 are extended to the non-active area NA1 and the seal pattern 40 is formed between the first and second substrates 10 and 20 in the non-active area NA1 to maintain a cell gap between the first and second substrates 10 and 20 and to prevent the liquid crystal material from leaking out. The seal pattern 40 is formed on one of the transparent first and second substrates 10 and 20 using a thermosetting resin. Then the transparent first and second substrates 10 and 20 are attached together by a thermo-compression bonding process. The liquid crystal display (LCD) device can be manufactured by a series of individual fabricating process steps including an array substrate fabricating process in which the thin film transistor “T” and the pixel electrode 17 are formed, a color filter substrate fabricating process in which the color filter 22 and the common electrode 23 are formed, and a liquid crystal cell process in which the array and color filter substrates 10 and 20 are attached together. Subsequently, the liquid crystal material is injected into the gap between the array and color filter substrates 10 and 20, and polarizers (not shown) are formed on outer sides of the array and color filter substrates 10 and 20.
The black matrix 21a is commonly formed along a boundary of each sub-color filter red (R), green (G), and blue (B) to prevent light from leaking out near the thin film transistor “T.” In addition, the black matrix 21 is formed along boundaries of the active area A1 to prevent the light from leaking out in the non-active area NA1. The black matrix 21 is commonly formed of organic materials, such as carbon (C) and chromium (Cr) thin films having an optical density of above 3.5.
The seal pattern 40 serves to maintain a uniform cell gap, prevents the injected liquid crystal material from leaking out of the device, and prevents moisture and air from penetrating into a liquid crystal cell of the device. The seal pattern 40 is commonly formed of an epoxy resin, and glass fibers or spacers are commonly used together with the seal pattern 40 to maintain the uniform cell gap. The epoxy resins used for forming the seal pattern 40 are commonly required to have low hardening-contraction ratios and high degrees of purity, and be non-contaminating and dimensionally stable. The epoxy resins may be classified into thermo-hardening resins that harden by application of heat, and photo-hardening resins that harden by irradiation of ultraviolet light.
The seal pattern 40 is commonly white, and is formed on the black matrix 21 that has been previously formed along the boundary region between the active area A1 and the non-active area NA1 to attach the array and color filter substrates 10 and 20. If adhesion between the black matrix 21 and the seal pattern 40 is excellent, then the seal pattern 40 can be formed directly on the black matrix 40. However, if adhesion between the seal pattern 40 and the resin black matrix is poor, the seal pattern 40 may delaminate from the resin black matrix.
FIG. 3A is a cross-sectional view of a liquid crystal display (LCD) panel having a chromium (Cr) black matrix structure of a seal pattern forming area between upper and lower substrates according to the related art. In FIG. 3A, if chromium (Cr) materials are used for a black matrix 310 formed on an upper substrate 300, a seal pattern 320 can be formed on upper and lower substrates 300 and 340 so that the seal pattern 320 directly contacts a surface of the black matrix 310. Here, “S1” is defined as a width of the seal pattern 320, “B1” is defined as a width of the black matrix 310, and active and non-active areas A1 and NA1 are defined on the liquid crystal display (LCD) device. The non-active area NA1 includes first and second portions having widths of L1 and C1, respectively. Thus, since the seal pattern 320 is formed on the black matrix 310, the width “B1” is equal to the width L1 of the first portion.
FIG. 3B is a cross-sectional view of another liquid crystal display (LCD) panel having a resin black matrix structure of a seal pattern forming area between upper and lower substrates according to the related art. In FIG. 3B, since adhesion of a resin black matrix 360 with a seal pattern 370 is poor, the seal pattern is not formed directly on the resin black matrix 360, but is formed at the side of the resin black matrix 360. For example, the seal pattern 370 is formed outside of an area where the resin black matrix 360 is formed to prevent the seal pattern 370 from delaminating from a surface of the resin black matrix 360. Here, “S2” is defined as a width of the seal pattern 370, and “B2” is defined as a width of the resin black matrix 360. The liquid crystal display (LCD) device includes active and non-active areas A2 and NA2, wherein the non-active area NA2 includes first and second portions having widths of L2 and C2, respectively. Accordingly, since the width L2 of the first portion is equal to a sum of the width S2 of the seal pattern 370 and the width B2 of the resin black matrix, i.e., L2=S2+B2, the width L2 of the first portion (in FIG. 3B) is larger than the width L1 of the first portion (in FIG. 3A), i.e., L1 <L2. Thus, the non-active area NA2 of the liquid crystal display panel having the resin black matrix is wider than the non-active area NA1 of the liquid crystal display panel having the chromium (Cr) black matrix. In addition, since the non-active areas NA1 and NA2 are not portions that display images, they both will be covered by an upper frame after liquid crystal module (LCM) processing in which the liquid crystal module is completed by attaching a backlight and upper and lower frames to the liquid crystal display panel. Accordingly, the liquid crystal display panel having the resin black matrix is limited with regard to manufacturing small-sized and lightweight liquid crystal display (LCD) devices.